Percussion tool



July 3, 1952 K. L. BERNINGER PERCUSSION TOOL Filed Oct. ll. 1949 2l alii-1.1.11, .4.5.1.1.

/NVENTQR m. fm R amc, L N M Kr 4; /4 7' TRNE-Y Patented July 8, 1952 PERCUSSION TOOL Kenneth L. Berninger, Dayton, Ohio, assignor of onefhalf to Wilbur F. Stover, Pleasant Hill,

Ohio

Application October 11, 1949, Serial No. 120,665

Claims.

tively slippery surface ofthe hard material toA be marked reaction forces in raising the hammer cause the holding hand to slide the tool ever so `little so that the hammer hits the tool when it is not'on the exact spot intended to be marked. An error therefore occurs, and is likely to be unobserved. To guard against such faults, and to provide a marking tool embodying its own hammer mechanism that will effectively and acc'u- I rately mark hard material, I make use of ahollow handle for slidably supporting'one end of a tool head, a rod-like hammer and a helical spring joined to the tool head and hammer under tension, with an actuating knob at the end of the housing for additionally stressing the spring when it is desired to applyV a hammer blow to the tool. The assembled length ofthe tool, hammer and knob is such, that it exceeds in length between a shoulder onv the tool head and the opposing end of the knob, the overall length of the housing, so that when the hammer and tool are engaged, then there is a looseness of the assembled tool head and hammer that permits a slight axial vrelative movement of the assembly within the housing,- the reason for whichwill presently appear. The housing or handle is intentionally of straight bore tubing with both endsopen with the same bore as the main bore of the tube to simplify the, act and method-of assembly, sincethe tool head may then be inserted inv either end of the tubular housing. The relation of the tubular housing, the spring connecting the tool head with the hammer rod, and the hammer are so proportioned in diameters that the spring acts as acylindrical-spacer and guidefor the movement of the hammerwhen striking the tool head. The reasonl for that will also appear as the description proceeds. L

Further objects and advantages of the present invention will be apparent from the following description, reference being made tothe drawings, wherein preferred embodiments of the present invention are clearly shown.

Y AIn the drawings:

y Fig. 1 is an elevational View of my improved 2 marking tool, With the hammer partly withdrawn.

Fig. 2 is a longitudinal sectional view substantially as indicated by the line and arrows2-2 of Fig. 1, but with the hammer fully housed as it normally is in the rest position.

Fig. 3 is an enlarged View similar to Fig. 2, the' better to illustrate some of the'ner details.

Fig. 4 is a fragmentary enlarged view of the juncture of tool head and handle applied to the work at the instant of marking the Work.

Fig. 5 is an enlarged fragmentary sectional view of the relation of parts insurings'moothness of operation and prompt delivery of power.

With particular reference to the drawings, I0 refers to a straight bore tubular housing or handle, and which encloses a hammer assembly I2 made up of a tool head I4 and, a hammer Arod I6, yieldablyretained in engagement at lI8 by a closely wound spiral spring 20, which is atf tached at one end 2I to the tool head I4 and Lend of the housing tube.

at the other endr to the hammer rod I6, at 23, the spring 20 being under such tension that the tool head I4 and the hammer rod I6 are firmly engagedat I8. That is made possible by bonding or otherwise securing one end of the spring 20 to a reduced stem or anvil 22 of the tool head I4, IThe hammer rod I6 is then passed Within the end of the spring until the rod engages the end of the anvil at I8. With the parts in that relation the spring is stretched somewhat until it approaches the top end of the rod where it is similarly attached as indicated at 23. The spring 20 is thereby stretched throughout' its length surrounding the rod l'between the attachments 2I and 23, and constitutes whatI choose to call ahammer assembly I2. The hammer assembly is then assembled in the tubular housing I0 by passing the top end where the spring is secured to the hammer rod at 23 into the bottom end of the housing, and moving along until it extends out of the other end, and until a cylindrical portion 24 of the tool head slides within one end of the tubular housing and a square shoulder 26 abuts the end of the tube as indicated at 28. The assembled length of the hammer assembly is such that the top end projects beyond the top The outside diameter of the cylindrical portion 24 is smaller by a few thousandths of an inch than the inside diameter of ther housing I0 that the tool head is capable of easily sliding in and out of the tubularhousing. While maintaining the tool head seated against the end of the housing I place about the top end an appropriate cavity filled, with a suitf 3 able plastic to form a knob 30. The attachments 2| and 23 may be accomplished by any one of several devices but I prefer a method that 32 of the knob adjacent the top end of the housing I and spaced therefrom somewhat as indicated at 34 in Fig. 3. Alternatively vl may cut the end of the knob to that facing and spacing after the moulding operation is completed.

When the knob is completed the overall length` between the shoulder 26 and the near end of the knob at 32 is greater by the amount of spacing 34 than the extreme length of the housing or handle i0. By reason of that, the hammer assembly I2 with the knob 3G attached can slide 'easily along the axis of the tubular housing I0 by the amount ofthe spacing 35 and yet'keep'the hammer and anvil engagement at |`8. Alsorotation of the knob 3B will effect yeasy rotation of the hammer assembly within the housing il). The only resistance to turning of the hammer assembly within the housing is the journalled relation of the end of the housing and the `cylindrical portion 24 of the tool head. The .inside and 'outside diameters lof the Vcoiled spring 2i) are such that the'spring 20 easily slides within the bore of the housing, and along the'outside of the hammer rod I5.

ments `and l,parts will not reduce thewound 'diameterV enough'to cause binding on thehammer rod I6.

Further, the section of the wire from which the spring is wound is suchthat i-the annular yspace 35 surrounding the rod and within vthe casing is substantially lled `by the turns of -the wound spring. The preferred relation Yof 'the housing Hl, the rod i6 andthe springQZil is better shown in Fig. 5 which is'an enlarged detail, in section. The spring 2am preference is aspring wherein the turns are closely spaced lwhen the spring is allowed to shorten Vto such the rod I6 and tube l@ is slightly greater than the diameter of the spring wire. By that con- The .inside diameter of :the wound spring is sufficiently greater than-the lcross section of the rod liV that stretching ythe Ispring tothe full capacity of the associated :ele-

tubular housing l0 may be knurled at 4| or near one Vend 42 to assist a firm linger grip on the tool. While the point of the tool is held in place against the workwith one hand the other hand grasps the knob and pulled away from the top of the housing to stretch the spring and ,y withdrawthe hammer rod from engagement with the anvil. The hammer rrod 'is' withdrawn a slight amount for a light blow and a greater amount for a heavier blow, all the time pressing downward with the lower end of the housing 'and tool head against the work. By releasing the ,knob 30 the spring quickly snaps the hammer rod'. i5 downward. against the anvil 22 and drives the tool head against the work. Fig. 4 shows `the relation of the parts as the hammer stroke takes place.

Thework is indicated at 50, as being-azsheet of metal to be marked with a center punch, and the point- 40 of the tool head is piercing the surface of the work at 52 somewhat the equivalent `of thespacing 54 between.

Vthe'end of the housing vand the shoulder '2 6 ,of

the tool head. The hammer rod |-6 and the anvil .2 2 are about tobe separatedat the meeting vpoint I8 incident to .the inertia of the tool v.head

i4 .being .actuated by a fully stretched fspring. That feature is made possible because of .the intended loose fit of thecylindrical portion 2470i the toolhead withintheendof the housing. All

of the stored energy of the stressed `spring I6 is expended in driving the tool head. ywhile the struction the end of the rod i6 sliding within .the Y spring is substantially like sliding withinfa 'continuous tube, and there is so little lateral Inovementbetween any two more of the elements i5, 20 and I0 that the rod i6 cannot sway 'enough to catch and hang up on the inside of one of the turns of the spring, even when the spring Vis stretched out beyond the end of thelhous'ing iii. That 'type of spring also makes it possible to obtain a relatively large amount of spring force by using Va relatively short length or wound spring, since the spring may be stretched a ccnsiderabie length without approaching the elastic limit of thespring. 'Y A".

In the use ofthe tool, the point dit of the tool head-whether it be a center punch, chisel point, or nail set, is placed against the work and held lwith one hand on the exact spot where the stroke is to be delivered. lThe outside of the housing held in the hand remains .substantially stationary, not being drivenby the hammer assembly. If Athe tool' head is :driven ,far Aenough beyond the end of 'the housing` that 'the cylindrical portion slides entirely out of ther end` of the housing, which-impossible under certainA conditions with the release Vv'of a fully stressed spring, the outside of the lower-end of the spring sliding within lthe lower en'd'of vthe housing will guidethe returno'f'the tool "head to its normal positionwithin'theend of the :housing after the stroke has been expended. i

Although a vspecific Vembodiment cf the invention hasbeen shown for the purposes of illustration, 4it -`will be evident that vthe invention is capable oifvarious modifications and adaptations'within the scope and spirito'ithe'appended claims.

` I claim:

l. A percussion tool'comprising in lcombination, atubular housing of uniform bore open at both ends, a tool head having a cylindrical shank slidably engaged in one end of the housing and a shoulder engageable with the end of the housing, a hammer rod engageable with the tool head and extending beyond the otherend of the housinga closely -wound helical spring extending the length 'of the housing and 'substantially lling the annular space between the inside of the housingv and the outside of the hammer rod, means anchoring one -end of Ythe spring to the tool head, the end turns ofthe other end Vof the spring being separated and tightly engageable about the extending end of 1 the hammer rod, said spring being stressed slightly while the hammer rod engages the tool head, and means anchoring the separated turns of the spring to the extending end ofthe hammer rod while 'the spring is slightly" stressed, ythereby normally keeping the hammer rod inengagement with the tool head, and means including the vextending endof the hammer rod f cr stressing the spring to store to the housing.

2. A percussion tool comprising in combination,

a tubular housing, a hammer assembly enclosed within the housing and including a tool head,

a hammer rod engaging the tool head, and a heliend to the tool head and v rod, means securing cal spring secured at one encompassing the hammer the other end of the spring to the remote end of the hammer rod, said spring when secured to the tool head and hammer rod being under light tension for normally engaging the hammer rod with the tool head, said tool head having a reduced portion with a shoulder movably supported in and against one end of the housing, said hammer asg sembly having the hammer rod and encompassing spring slidably associated with the inside of the housing and the remote end thereof extending beyond the end of the housing when the shoulder of the tool head is against the other end of the housing, and a knob secured to the remote end of the hammer assembly for stressing the spring i While holding the tool head against the work,

whereby release of the stressed spring permits the hammer rod to strike the tool head and drive the tool head out of the housing somewhat without expending energy to drive the housing.

3. The combination set forth in claim 2 wherein the means securing the said other end of the spring to the remote end of the 'hammer rod/'in-l cludes spaced end turns of the spring being bonded to the end of the rod and providing anchorage for the knob moulded thereon. i

4. The combination set forth in claim 2 Wherein the assembled length of thev hammer assembly is such that the distance between the shoulder of the tool head and the near end of the knob ex-l ceeds the overall length of the housing so that; striking of the hammer rod upon the tool head drives the tool head against the work without eifecting movement of the housing.

5. A variable stroke percussion tool comprising'iin combination, an operating assembly includv ing a tool head having a shouldered cylindrical portion and an axially extending anvil, a hammer rod aligned with the anvil, a helical spring loosely encompassing the hammer rod and having its ends deformed to firmly engage about the Lanvil and the end of the rod remote from the anvil, means securing the ends of the spring to the anvil and to the remote end of the rod )so that the spring will be slightly tensioned when the end of the hammer rod is engaging the anvil, a tubular housing of uniform bore within which the said operating assembly may be inserted until the shoulder of the cylindrical portion of the tool head engages the end of the housing and the cylindrical portion slidably engages the bore'of the housing, and a knob secured to the end of the hammer rod about the secured end of; the spring, said knob having an annular shoulder spaced from the adjacent end of the housing when the tool head shoulder engages the ilrst'mentioned end of the housing, said tubular housing loosely encompassing the spring and extending throughout the active portion thereof to guide the spring and hammer rod when there is relative movement thereof with respect to the housing, whereby the hammer rod is always aligned with the anvil during a percussion stroke.

KENNETH L. BERNINGER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 

